The 'three in a row' pattern, with a motorist driving down the centre of the carriageway in order to get both sets of wheels in the gaps. Speed cushions encourage drivers to continue down the middle of the road, to the detriment of cyclists coming in the opposite direction.

These cushions (below, on Grove Road E17) are stupidly sited at a pedestrian crossing point between Beulah Path and College Road - just the place where drivers ought not to be encouraged to swerve erratically in order to drive through the gaps.

Fourthly, the rubber ones (which, like those in the photographs above, are the ones mostly used in Waltham Forest) are slippery in wet weather.

So: speed cushions don’t cut speed and actually make roads more dangerous for cyclists. Why, then, do local authorities continue to install them?

Basically because both bus companies and the emergency services don’t like road humps. They make for a bumpy bus ride. And they slow down fire engines, police cars and ambulances. Whereas speed cushions can be driven over at much faster speeds, without so much vibration.

The London Ambulance Service has always been the most vocal critic of road humps (and is frequently quoted on petrolhead websites like the self-styled ‘Association of British Drivers’). The London Ambulance Service has claimed that the 30,000 humps on the capital’s roads cause up to 500 deaths a year because its crews suffer delays in reaching victims of cardiac arrest. That suspiciously neat statistic needs to be regarded with scepticism. It appears to have no support from other health professionals.

It is also the case that the London Ambulance Service is conspicuously silent about road deaths as a health issue.

In fact slowing down ambulances may not always be a bad thing, bearing in mind that London ambulances are involved in an average of more than four crashes a day. These crashes cost more than £300,000 a month in compensation, legal fees and repair bills.

Road humps are a very crude way of slowing down vehicles. The technology exists to fit every motor vehicle with a device which would automatically reduce speed to match the speed limit. This is opposed by the motor lobby, which even resists ‘black box’ technology, which would record vehicle speed at the time of a collision.

Ironically such technology was developed to research airbags inflating when drivers went over road humps and is now fitted to luxury cars as an incidental accessory:

Singh's trial used evidence from a device fitted to the airbag system of his Range Rover - the first time such technology has played a role in a British court. The Event Data Recorder, similar to an aircraft's black box, was used to establish that a force equivalent to 42mph was lost in one fifth of a second in the crash. This helped police put the defendant's speed at around 72mph.

Road humps, for all their crudity, have a track record of success in reducing casualties. Speed cushions, by contrast, are irrational, ineffective and potentially dangerous to cyclists and pedestrians. Instead of making the roads safer they are more likely to deter cycling by agitating traffic, not calming it.

But they continue to be installed, and the London Borough of Waltham Forest has no plans to get rid of the ones which now exist on scores (hundreds?) of local streets. As always, so-called ‘road safety’ is determined by politics rather than science and rationality.

And it is characteristically dishonest of this Council to claim that speed cushions ‘are preferred by…cyclists’ to road humps. They aren’t.